Reorganize codebase into modular structure

src/app/messages.rs

@@ -0,0 +1,14 @@
+// Application messages
+
+// Messages that can be sent in our application
+#[derive(Debug, Clone)]
+pub enum Message {
+    NextCursor,
+    SelectCursor(usize),
+    Quit,
+    TrayEvent, // Used as a no-op message
+    CloseRequested(iced::window::Id), // Message for window close requests with the real window ID
+    ShowWindow, // Message to show the window from tray
+    WindowHidden, // Message indicating window was successfully hidden
+    WindowShown, // Message indicating window was successfully shown
+}